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L-Histidine
Precursor to both histamine and carnosine, supporting immune response, stomach acid production, and intracellular antioxidant defense.
What the evidence says
L-Histidine appears to help in 7 of 7 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1975–2026 with a typical study size of 31 participants.
Based on 28 studies · 1 meta-analysis · 13 RCTs · 7,983 total participants
Confidence
HighWhat the studies found
By outcome
L-Histidine has an evidence score of 8.5/10 — very strong evidence based on 28 indexed studies, including 3 meta-analyses. Precursor to both histamine and carnosine, supporting immune response, stomach acid production, and intracellular antioxidant defense.
The commonly studied dose of L-Histidine is 1-4g daily. Research points to an estimated optimal dose around 3g, with a minimum effective dose near 1g. Individual response varies — start low and adjust.
The best time to take L-Histidine is between meals. It can be taken on an empty stomach. L-histidine is a conditionally essential amino acid that serves as a precursor to histamine, carnosine, and the metalloenzyme cofactor 3-methylhistidine.
L-Glutamine
Likely helpsPrimary fuel for intestinal and immune cells — becomes conditionally essential during stress, illness, or intense training.
Arginine
Probably helpsPrimary substrate for nitric oxide production — dilates blood vessels to improve circulation, exercise performance, and cardiovascular health.
Last reviewed May 2026 · evidence from 39 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
L-Histidine is an essential amino acid particularly important during growth periods. It's the precursor to histamine (involved in immune response, stomach acid, and neurotransmission) and combines with beta-alanine to form carnosine (an intracellular antioxidant). It plays roles in immune function, wound healing, tissue repair, and is a component of hemoglobin. Low histidine has been linked to rheumatoid arthritis and anemia.
Converted to histamine
Combines with beta-alanine to form carnosine
Important for oxygen transport
How L-Histidine works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
1-4g daily
Loading: Not required
Can be taken without food
| Form | Type |
|---|---|
| 💊L-Histidine powder or capsules | Recommended |
Pure L-histidine is standard. Often included in EAA blends.
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Best absorbed on empty stomach. Those with histamine intolerance should be cautious.
Based on limited evidence showing 34% reduction in SCORAD index. Studies are preliminary with small sample sizes. Risk of histamine-related symptoms in sensitive individuals.
Supported immune response
Enhanced carnosine levels
Support for wound healing
Some studies show low histidine levels; supplementation may help
Histidine converts to histamine; may reduce antihistamine effectiveness
Folic acid deficiency can cause FIGLU buildup with histidine use
Tip: Start low; avoid if histamine intolerant
L-Histidine is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are histamine-related symptoms. Use caution if any of these apply to you: Histamine intolerance (may worsen symptoms); Mast cell disorders.
SAMe
Mostly mechanism / observationalDrives 100+ methylation reactions including neurotransmitter synthesis — clinically validated for depression, osteoarthritis, and liver health.
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